The present invention relates to a clamp. More particularly this invention concerns a slide- or jam-type L- or bar clamp.
A standard L- or bar clamp has a straight bar along which can slide a movable arm or jaw whose outer end is traversed by a threaded spindle having on one end a crank or handle and on the opposite end an abutment pad. One end of the bar is formed or provided with a transverse fixed arm or jaw whose outer end is also provided with an abutment pad aligned in a longitudinal direction parallel to the bar with the pad of the spindle. The movable jaw can be slid along the bar and jammed tight in any of a multiplicity of longitudinally offset positions for a coarse setting of the abutment-pad spacing. Thus for use the objects being clamped are positioned between the pads, then the movable jaw is slid in until the movable pad presses the objects against the fixed pad, and finally the spindle is cranked to force the movable pad against the objects.
As described in German patent document 4,236,049 of Mayer, the fixed arm is unitarily formed with the bar. To this end the bar is simply C-shaped at one end to form the fixed arm. Such an arrangement is not sufficiently strong.
In German patent document 197 48 130 of Kopf the bar is basically L-shaped with the short leg forming the fixed arm and the long leg the slide bar. Such a system is also not capable of withstanding the considerable forces that often need to be applied.
U.S. Pat. No. 4,336,927 of Goff describes a spring-type clip where a movable part slides along a round-section rod having a bend-out corner. This system has no screw-type clamping system, and is purely intended for light-duty clamping operations.
It is therefore an object of the present invention to provide an improved heavy-duty jam-type clamp.
Another object is the provision of such an improved heavy-duty jam-type clamp which overcomes the above-given disadvantages, that is which is quite strong and that still can be tightened by standard screw action.
A bar clamp has according to the invention a straight and stiff metal bar having an straight inner face, a straight and stiff fixed metal arm extending from an end of the bar and having a straight inner face substantially perpendicular to the bar inner face, and a metal corner unitarily formed with the bar and arm and joining the bar to the arm. A longitudinally facing abutment pad is carried on an outer end of the fixed arm. The corner has an arcuate inner face joining the bar and arm inner faces, offset outward from planes lying on the bar and arm inner faces, and symmetrical to a bisector extending through a point where the planes meet. A movable arm can slide longitudinally along the bar and carries a tightening mechanism in turn carrying an abutment confronting the fixed-arm abutment and longitudinally displaceable relative to the movable arm toward and away from the fixed-arm abutment.
With this type of corner construction the clamp has considerable strength due to the arcuate shape of the corner. At the same time it can be cozied up very close to a workpiece, for instance a counter top, from whose corner something projects, as this projection can be accommodated by the outwardly offset clamp corner. The rounded shape is very strong and any elastic deformation of the clamp will be in a direction preventing the clamp from slipping off the objects held between its abutments.
According to another feature of the invention the corner has a circularly arcuate inner face joining the bar and arm inner faces, offset outward from planes lying on the bar and arm inner faces, and having a center of curvature substantially at the point where the planes meet.
The corner inner face in accordance with the invention extends relative to the center over about 270xc2x0. Furthermore the bar, corner, and fixed arm are of continuous unchanging cross-sectional shape and have a predetermined width. The radius of curvature of the corner inner face is equal to between 50% and 100% of the bar width.
The tightening mechanism according to the invention includes a spindle threaded into the outer end of the movable arm and having one end carrying the movable-arm abutment an opposite end carrying a handle.